Structuring Graphical Paradigms in TkGofer

Abstract

In this paper we describe the implementation of several graphical programming paradigms (Model View Controller, Fudgets, and Functional Animations) using the GUI library TkGofer. This library relies on a combination of monads and multiple-parameter type classes to provide an abstract, type safe interface to Tcl/Tk. We show how choosing the right abstractions makes the given implementations surprisingly concise and easy to understand. 1 Introduction In his article `Why Functional Programming Matters' [7], John Hughes explains that an important feature of a programming language is the way in which a language provides glue for combining building blocks to form larger structures. The better the glue, the more modular programs can be made. He argues that functional languages offer very powerful kinds of glue like higher order functions and lazy evaluation. Further research evolved a new kind of glue: type and constructor classes [9]. Unfortunately, there used to be a separation between th...